Does Miso Paste Go Bad? How Long Will It Last?

Does miso paste go bad? If you have leftover miso paste that hasn’t been used for a while and are wondering whether to toss or use for cooking… read on for tips about how long miso paste lasts and everything else you need to know!

store-bought miso paste and homemade miso paste.

Your miso paste has been open for too long, and you’re wondering if it’s still good to use…

Don’t be unsure about the freshness of miso paste – this article will provide helpful information to determine if it’s still alright to use!

Read on to find out more! Let’s dive in!

What is Miso Paste?

two types of miso paste. white miso and red miso.
Red miso (left) and white miso (right)

Miso paste is fermented soybean paste and preservative food. This fermented product is an essential condiment in Japanese cuisine. It’s nutritious and great for gut health (see the health benefits here).

Click to get more information about what is miso paste.

How Long Does Miso Last?

white miso paste.

Traditional miso paste has a remarkably long shelf life, typically ranging from 3 months to 12 months, depending on the variety. This extended freshness is primarily due to the high salt content in miso, which acts as a preservative, ensuring that the miso stays fresh for an extended period.

While miso paste doesn’t go bad easily, its taste can deteriorate over time. However, it’s important to be aware that low-salt or processed miso varieties, especially those with added soup stock, might be more likely to go bad.

For Example…

3 types of miso paste by its color.

As I mentioned earlier, the shelf life of miso paste can vary depending on the type you use. Here are some examples of expiration dates:

  • White miso paste: 6 months
  • Red miso paste: a year
  • Reduced sodium miso paste: 6 months
  • Homemade miso paste: a year or more

Can You Use Miso Paste Past the Expiration Date?

a label of miso paste.

Yes, you can, but it may not depend on how it’s stored.

Even though it has a best-by date, as a preservative food, it lasts way beyond the date and can be enjoyed over time.

However, suppose it is stored in a warm environment for a long time. In that case, you might see some deterioration in miso paste as heat and high humidity speed up the fermentation process.

Signs of Spoilage?

homemade miso paste.

How do you know if a miso paste is bad? Since it’s a fermented food, it continues to develop its flavor. If it’s not stored correctly, you might see some signs of going bad.

Is this bad? Is this OK to eat? Here are some samples you might run into if you haven’t used miso for a while.

1. The Color is Darker than Before

two types of miso paste side by side.
Homemade miso paste, left: 18 months, right: 8 months

You may find your miso paste is darker before and wondering if this is ok to eat?

The longer the time passes, the more miso’s color changes and gets darker (called the Maillard reaction). Darker miso is matured. So it’s natural as fermentation goes on all the time.

The taste also changes to a less sweet and deeper flavor. Some people love this aged miso flavor, and some prefer a light and sweeter one.

If you like the taste of dark color miso or mature miso, you can keep using it.

2. It Tastes Sour

If your miso has a sour taste, it is likely due to the fermentation process going on for too long.

You can still eat it, but it doesn’t taste good. It’s probably best to avoid consuming it.

3. White Mold Grows

You might encounter the white fluffy mold on miso paste, and it’s common.

You don’t need to panic. It only grows on the surface of the miso, so you remove about an inch from where the mold is growing; after that, you can eat it safely.

However, if you use reduced sodium miso or the one with dashi stock, be careful – these molds could indicate going bad. If it smells strange, it would be better to throw it away.

4. Smells Bad

When you realize that it smells different…if it smells like alcohol, it’s okay because a small amount of alcohol occurs during fermentation.

If it smells strange or wrong, you should stop using it.

How to Store Miso Paste

miso paste in an airtight container.

Where is the best place to keep miso paste?

The storage conditions are critical to keep the good quality fresh miso. The best way is to keep it in low temperatures. So, I highly recommend putting it in an airtight container and storing it in the fridge.

Even unopened miso keeps fermenting, so storing it in the fridge is also better.

If the surface of the miso dries up in the refrigerator, cover it with plastic wrap and close the lid.

If you prefer to store miso at room temperature, keep it in a cool, dark place, like kitchen cabinets. (Room temperature should be less than 25 degrees.)

Click here for a complete guide on How to store miso paste.

The Best Way to Use Old Miso Paste

3 miso paste dishes.

If your miso paste is not so fresh, but you don’t want to toss it, here are the best ways to use up your old miso!

  • Miso mayo: Mix miso paste and mayonnaise. Use it as a dipping sauce for vegetable sticks.
  • Miso salad dressing: Mix miso paste, vinegar, sugar, and olive oil and make a salad dressing.
  • Misozuke (pickle): Make a pickling mixture with miso paste and mirin. Pickle vegetables (carrot, daikon, cucumber, etc.) or tofu overnight.
  • Stir fry: Make a mixture with miso paste, soy sauce, and mirin. Use it as stir-fry seasoning.

Japanese Miso Soup Recipes

6 miso soup images.

Looking for a delicious way to use up your miso paste? Check out these Miso Soup Recipes. I share 10 easy-to-follow miso soup recipes that you can make at home.

Miso soup is the most simple and easy dish in Japanese cooking. I hope you will enjoy the authentic flavor!

Thanks For Stopping By!

Thank you for taking the time to read my blog♡. If you’ve tried this recipe (or any other recipe on the blog), please give it a star rating below!

Also, feel free to leave comments if you have any questions. I love hearing from you!

Chef JA Cooks is a Japanese food blog that shares simple and healthy Japanese home cooking recipes, including vegan and vegetarian. From traditional Japanese recipes to modern recipes with step-by-step instructions.

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